Problem: $ { \left[\begin{array}{r}{-1} \\ {-1} \\ {3}\end{array}\right]-\left[\begin{array}{r}{3} \\ {-1} \\ {1}\end{array}\right] = {?} } $
Answer: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{r}{-1}-{3} \\ {-1}-{-1} \\ {3}-{1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{r}{-4} \\ {0} \\ {2}\end{array}\right]}$